Harvard Radiation Oncology Program, Boston, MA, USA.
Int J Radiat Oncol Biol Phys. 2012 Jun 1;83(2):533-41. doi: 10.1016/j.ijrobp.2011.08.003. Epub 2011 Nov 16.
To evaluate patients with high-risk cerebral arteriovenous malformations (AVMs), based on eloquent brain location or large size, who underwent planned two-fraction proton stereotactic radiosurgery (PSRS).
From 1991 to 2009, 59 patients with high-risk cerebral AVMs received two-fraction PSRS. Median nidus volume was 23 cc (range, 1.4-58.1 cc), 70% of cases had nidus volume ≥ 14 cc, and 34% were in critical locations (brainstem, basal ganglia). Median AVM score based on age, AVM size, and location was 3.19 (range, 0.9-6.9). Many patients had prior surgery or embolization (40%) or prior PSRS (12%). The most common prescription was 16 Gy radiobiologic equivalent (RBE) in two fractions, prescribed to the 90% isodose.
At a median follow-up of 56.1 months, 9 patients (15%) had total and 20 patients (34%) had partial obliteration. Patients with total obliteration received higher total dose than those with partial or no obliteration (mean dose, 17.6 vs. 15.5 Gy (RBE), p = 0.01). Median time to total obliteration was 62 months (range, 23-109 months), and 5-year actuarial rate of partial or total obliteration was 33%. Five-year actuarial rate of hemorrhage was 22% (95% confidence interval, 12.5%-36.8%) and 14% (n = 8) suffered fatal hemorrhage. Lesions with higher AVM scores were more likely to hemorrhage (p = 0.024) and less responsive to radiation (p = 0.026). The most common complication was Grade 1 headache acutely (14%) and long term (12%). One patient developed a Grade 2 generalized seizure disorder, and two had mild neurologic deficits.
High-risk AVMs can be safely treated with two-fraction PSRS, although total obliteration rate is low and patients remain at risk for future hemorrhage. Future studies should include higher doses or a multistaged PSRS approach for lesions more resistant to obliteration with radiation.
评估因位于功能区或体积较大而具有高风险的脑动静脉畸形（AVM）患者，这些患者接受了计划的两分割质子立体定向放射外科手术（PSRS）治疗。
1991 年至 2009 年间，59 例具有高风险脑 AVM 的患者接受了两分割 PSRS 治疗。病灶体积中位数为 23cc（范围，1.4-58.1cc），70%的病例病灶体积≥14cc，34%的病例病灶位于关键部位（脑干、基底节）。基于年龄、AVM 大小和位置的 AVM 评分中位数为 3.19（范围，0.9-6.9）。许多患者曾接受过手术或栓塞治疗（40%）或之前接受过 PSRS（12%）治疗。最常见的处方是两分割 16Gy 放射生物学等效剂量（RBE），处方剂量为 90%等剂量线。
中位随访时间为 56.1 个月时，9 例（15%）患者完全闭塞，20 例（34%）患者部分闭塞。完全闭塞的患者接受的总剂量高于部分闭塞或未闭塞的患者（平均剂量，17.6 与 15.5Gy（RBE），p=0.01）。完全闭塞的中位时间为 62 个月（范围，23-109 个月），5 年部分或完全闭塞的累积发生率为 33%。5 年累积出血发生率为 22%（95%置信区间，12.5%-36.8%），14%（n=8）的患者发生致命性出血。AVM 评分较高的病变更易出血（p=0.024），对放疗的反应较差（p=0.026）。最常见的并发症是急性（14%）和长期（12%）1 级头痛。1 例患者出现 2 级全身性癫痫发作障碍，2 例患者出现轻度神经功能缺损。
尽管完全闭塞率较低，且患者仍有发生未来出血的风险，但高风险 AVM 可以安全地用两分割 PSRS 治疗。未来的研究应包括更高剂量或多阶段 PSRS 方法，以治疗对放疗闭塞反应较差的病变。
